[PGO] Profile guided code size optimization.

Summary:
Enable some of the existing size optimizations for cold code under PGO.

A ~5% code size saving in big internal app under PGO.

The way it gets BFI/PSI is discussed in the RFC thread

http://lists.llvm.org/pipermail/llvm-dev/2019-March/130894.html 

Note it doesn't currently touch loop passes.

Reviewers: davidxl, eraman

Reviewed By: eraman

Subscribers: mgorny, javed.absar, smeenai, mehdi_amini, eraman, zzheng, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59514

llvm-svn: 358422

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index f35328ca8d4..23b88dbda26 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -16,8 +16,10 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/Analysis/ProfileSummaryInfo.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Analysis/ValueTracking.h"
@@ -34,6 +36,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/KnownBits.h"
 #include "llvm/Transforms/Utils/BuildLibCalls.h"
+#include "llvm/Transforms/Utils/SizeOpts.h"
 
 using namespace llvm;
 using namespace PatternMatch;
@@ -2375,7 +2378,9 @@ Value *LibCallSimplifier::optimizeFPuts(CallInst *CI, IRBuilder<> &B) {
 
   // Don't rewrite fputs to fwrite when optimising for size because fwrite
   // requires more arguments and thus extra MOVs are required.
-  if (CI->getFunction()->hasOptSize())
+  bool OptForSize = CI->getFunction()->hasOptSize() ||
+                    llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI);
+  if (OptForSize)
     return nullptr;
 
   // Check if has any use
@@ -2750,9 +2755,10 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
 LibCallSimplifier::LibCallSimplifier(
     const DataLayout &DL, const TargetLibraryInfo *TLI,
     OptimizationRemarkEmitter &ORE,
+    BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
     function_ref<void(Instruction *, Value *)> Replacer,
     function_ref<void(Instruction *)> Eraser)
-    : FortifiedSimplifier(TLI), DL(DL), TLI(TLI), ORE(ORE),
+    : FortifiedSimplifier(TLI), DL(DL), TLI(TLI), ORE(ORE), BFI(BFI), PSI(PSI),
       UnsafeFPShrink(false), Replacer(Replacer), Eraser(Eraser) {}
 
 void LibCallSimplifier::replaceAllUsesWith(Instruction *I, Value *With) {